1. Field of the Invention
The present invention relates to method for manufacturing device isolation film of semiconductor device, and in particular to an improved method for manufacturing device isolation film wherein a high selectivity slurry containing MxPyOz is used for polishing nitride film to prevent the generation of moat, thereby improving the characteristic of the device.
2. Description of the Background Art
FIGS. 1a through 1f are cross-sectional diagrams illustrating a conventional method for manufacturing device isolation film of semiconductor device.
Referring to FIG. 1a, a pad oxide film 20 and a pad nitride film 30 are sequentially formed on a semiconductor substrate 10.
Referring to FIG. 1b, the pad nitride film 30, the pad oxide film 20 and the semiconductor substrate 10 are etched to form a trench 40.
Referring to FIG. 1c, an oxide film 50 is formed on the inner surface of the trench. Thereafter, a liner nitride film 60 is formed on the entire surface including the inner surface of the trench 40.
Referring to FIG. 1d, an oxide film for device isolation film 70 filling the trench 40 is formed on the entire surface.
Referring to FIGS. 1e and 1f, the oxide film for device isolation film 70 is polished until liner nitride film 60 is exposed. The liner nitride film 40 and the pad nitride film 30 are then removed to form a device isolation film 80.
In accordance with the conventional method for manufacturing device isolation film of semiconductor device, a moat denoted as “a” in FIG. 1f is generated during the etching processes of the liner nitride film and the pad nitride film and a subsequent cleaning process. Residues are accumulated in the moat, which degrades the characteristic of the device.